1. Field of the Invention
This invention relates generally to data processing systems and more particularly to apparatus coupling the central subsystem with peripheral subsystems. The coupling apparatus provides the means for transferring signal groups between the central subsystem and the peripheral subsystems.
2. Description of the Prior Art
It is known in the prior art to provide input/output apparatus coupling a central subsystem and peripheral subsystems that in response to the initiation of a predetermined operation involving the transfer of signals between the two subsystems, preempts further use of the input/output apparatus until completion of the predetermined operation. Because an operation can typically involve the exchange of a multiplicity of signal groups, and can typically involve a peripheral device with significantly slower operating characteristics as compared to the central subsystem, the performance of the entire data processing system can be impacted.
In order to maintain an efficient flow of information between the two subsystems, various techniques have been devised to improve the system's performance. For example, priority assignments can be instituted in the central subsystem so that operation essential for the efficient operation of the central processing unit of the central subsystem are performed prior to the less essential operations. Similarly, look-ahead techniques can be implemented so that operations can be performed, such as data signal group transfers, prior to the requirement by the central subsystem, thereby permitting a non-essential operation to be performed during a period of relative inactivity.
While these techniques and others have been implemented, the ever-increasing speed of the central processing unit has lead to a requirement of increasing efficiency of operations involving the central subsystem and peripheral subsystems.
It is therefore an object of the present invention to provide an improved data processing system.
It is another object of the present invention to provide improved apparatus coupling the central subsystem and the peripheral subsystem of a data processing system.
It is yet another object of the present invention to provide improved performance in execution by central subsystem instructions involving the peripheral subsystems.
It is a more particular object of the present invention to provide apparatus for coupling the central and peripheral subsystems that permits concurrent execution of a multiplicity of operations.
It is yet another particular object of the present invention to provide apparatus coupling a central subsystem with peripheral subsystems in which a plurality of signal group manipulations can be performed independently.
It is still another particular object of the present invention to provide apparatus coupling the central subsystem and the peripheral subsystems permitting independent execution of portions of a multiplicity of concurrent operations.